A liquid flows through an “equal percentage” valve at a rate of $2\:m^{3}/h$ when the valve is $10\%$ open. When the valve opens to $20\%$ the flowrate increases to $3\:m^{3}/h$. Assume that the pressure drop across the valve and the density of the liquid remain constant. When the valve opens to $50\%$, the flowrate (in $m^{3}/h$, rounded off to the second decimal place) is________________________________